I really like that it is easy to use, has great templates for all sizes of companies so you can get started right away without having too much work ahead! The only thing about this program as far are my clients who have been using other programs in which they do not want me or any one else from our office working with them anymore because their emails look very similar when compared side by side (even though we make changes).
If there was something different between these two products then maybe more people would be happy but if everything looks pretty close than why change? It's just easier sometimes since everyone knows how an agency should send out information instead trying new things every time someone gets bored/doesn't know what will sell best etc.. This makes sure nothing goes wrong once sent off into cyberspace :).